Pressure compensated load sense hydraulic systems are used in many industries, including for example mobile construction and forestry equipment. Pressure compensated load sense systems allow for better multi-functioning performance due to improved flow sharing with pressure compensation. Without pressure compensation, the flow in a hydraulic system will go to the flow path of least resistance. For example, when commanding two functions (F1 and F2) in a hydraulic system with more flow than the flow source can provide, uneven flow sharing will occur when the two functions have differing loads. In a situation where the max pump flow is 10 GPM (gallons per minute) and a flow of 10 GPM is being commanded to each of the two functions F1 and F2, where F1's load requires 3000 psi (pounds per square inch) to move and F2's load only requires 1000 psi to move, then F2 will move first and F1 will not move until F2 stops being commanded or reaches a physical limit such as the end of stroke of a cylinder. Pressure compensators can be added to hydraulic systems to improve this situation.
If pressure compensation is added to the hydraulic system in the same example as above, each function F1 and F2 will get a portion of the max flow based on each function's percentage of the sum of the requested flow. This is accomplished through a pressure balance using a pressure compensator for each of the functions F1 and F2. The highest function load (3000 psi) is applied on one side of each pressure compensator trying to force that compensator closed, and the individual function's load (3000 psi for F1, and 1000 psi for F2) on the opposite side of the compensator trying to force the compensator open. The compensator of the lower loaded function F2 will be forced closed since the highest function load will be higher than the lower loaded function's load. This added restriction to the lower loaded function will make both flow paths to F1 and F2 have equal resistance allowing flow sharing between two unequally loaded functions. In this situation, F1 flow request is 10 GPM and the F2 flow request is 10 GPM for a total requested flow of 20 GPM. Since the F1 flow request is 50% of the sum of the requested flow, F1 will get 50% of the available pump flow which is 5 GPM. And since the F2 flow request is also 50% of the sum of the requested flow, F2 will get 50% of the available pump flow, 5 GPM, as well.
Although pressure compensation has the benefit of flow sharing, the pressure compensators introduce added restriction and loss in power that results in heat production. When multifunctioning, the larger the difference between the smallest and greatest load, the larger the amount of heat that is produced. The power lost to heat is represented by the following fluid power equation:Power=P*Q/1714
where:                P=the pressure drop across the compensator in PSI,        Q=the flow rate through the compensator in GPM, and        Power=the power loss in horsepower (HP).        
It would be desirable to reduce the pressure difference between functions requesting flow in a pressure compensated hydraulic circuit to reduce the power loss and heat production of the pressure compensation.